Pull bar construction for solenoids



June 29, 1954 SQRENG ETAL 2,682,625

PULL BAR CONSTRUCTION FOR SOLENOIDS Filed Jan. '7, 1952 Jan/M23 Edgar M Eavenq Ember? YY. Basin Patented June 29, 195 4 PULL BAR CONSTRUCTION FOR SOLENOIDS Edgar M. Soreng, Skokie, and Robert W. Bachi, Itasca, Ill., assignors, by mesne assignments, to Soreng Products Corporation, a corporation of Delaware Application January '7, 1952, Serial No. 265,266

This invention relates to solenoids having plungers and refers more particularly to a novel pull bar for connecting the plunger of a solenoid with the load to be actuated by the plunger.

While this invention may be advantageously applied to the plungers of both alternating and direct current solenoids of a Wide variety of types, its nature and advantages are perhaps most readily appreciated in connection with alternating current solenoids of the type having a 1 substantially C-shaped frame embracing the coil and a T-shaped plunger, such as that shown in the patent to Hardin Y. Fisher, No. 2,468,052; and consequently the invention will be herein described with particular reference to a solenoid of that type, although it will be understood that this is merely by way of example.

Heretofore in such A. C. solenoids the side plates of the plunger were extended beyond the outer end of the plunger itself and the load (1. e., the part to be actuated) was connected to the plunger by means of a cross pin, the ends of 3 Claims. (Cl. 317-491) which were secured in the extensions of the side plates. The resulting connection between the plunger and its load was relatively rigid, and it was therefore necessary that the solenoid be mounted with extreme accuracy in most installations since any disalignment between the plunger axis and the load force tended to cock the plunger angularly to one side and caused the plunger to bind in its guides. inner surfaces of the head of a T-shaped plunger would not seat securely against the cooperating surfaces of the solenoid frame unless the load were almost perfectly aligned with the plunger axis, and consequently in solenoids of that type such disalignment not only created excessive sliding friction of the plunger in its guides but also caused excessively noisy operation as a result of this imperfect seating.

This cocking of the plunger, as well as the undesirable consequences thereof, was further aggravated in the case of solenoids having plungers of the T-head type because, as may be readily seen by reference to the above identified patent to Fisher, the point of attachment of the load to the plunger was situated a substantial distance outwardly of the inner surfaces of the lateral extensions comprising the plunger head, and therefore any sideward component of the load force (due-to disalignment between the plunger axis and the load force) was exerted upon the plunger through a considerable lever arm. An additional disadvantage of this type of construction resided in the fact that the load force reaction was transmitted to the plunger at' Moreover, the

points spaced from the axis thereof, and any eccentricity in the load reaction was therefore further magnified by the fact that it was transmitted unequally to opposite sides of the plunger, creating a very definite couple thereon.

With these and other objections to previously known pull bar constructions in mind, it is an object of this invention to provide a novel pull bar for the plunger of a solenoid, which pull bar is so secured to the plunger that the undesirable effects of disalignment between the plunger axis and the load to be actuated by the plunger will be minimized or even entirely eliminated.

Another object of this invention resides in the provision of a pull bar for the plunger of a solenoid of the character described, which pull bar will have a limited degree of universal motion to accommodate disalignment between the plunger axis and the load force and which, moveover, will be very inexpensive to manufacture.

Still another object of this invention resides in v the provisions of a pull bar of the character described which is so connected to a solenoid plunger of the T-head type that the load force will be applied to the plunger substantially coaxially therewith and at a point spaced inwardly of its outer end and adjacent to the plane containing the inner surfaces of the lateral extensions comprising the plunger head, so that the angular component of any non-axial force on the plunger due to disalignment between the plunger axis and the load will be exerted close to the plane of the seating surfaces and will thus have less tendency to cook the plunger askew.

With the above and other objects in View, which will appear as the description proceeds, this invention resides in the novel construction, combination and arrangement of parts substantially as hereinafter described and more particularly defined by the appended claims, it being understood that such changes in the precise embodiment of the hereindisclosed invention may be as come within the scope of the claims.

The accompanying drawing illustrates one complete example of the physical embodiment of the invention constructed according to the best mode so far devised for the practical application of the principles thereof, and in which:

Figurel is a side elevational view of an alternating current solenoid of the T-head plunger type equipped with the pull bar of this invention;

Figure 2 is an enlarged fragmentary sectional view through the plunger taken along the plane of the line 22 in Figure l; and

Figure 3 is a sectional view taken along the plane of the line 3-3 in Figure 2.

Referring 110w to the accompanying drawing in which like numerals designate like parts throughout the several views, the numeral 5 designates generally an alternating current solenoid having a plunger 6 of the T-head type. While the invention will be described with particular reference to a solenoid of this type, it will be understood that it is equally applicable to the plungers of other types of alternating and direct current solenoids.

The solenoid has a substantially C-shaped frame 1 composed, as is well known, of a number of substantially identical laminae. Substantially 'l"shaped plunger guides are secured to opposite sides of the frame and the stem 9 of the plunger 6 is endwise slidably mounted in the channel-like stem portions of the plunger guides, while a coil it is mounted on said stem portions of the plunger guides, within the frame, and thus embraces the plunger stem.

The plunger, like the frame, is made up of a number of substantially identical laminae of magnetically permeable material. Side plates 4 l at the sides of the plunger stem provide bearing surfaces which cooperate with the plunger guides to mount the plunger stern for endwise sliding movement.

The plunger has opposite lateral extensions l2 at its outer end, forming the head of the T, and the inner faces 53 of these extensions are substantially coplanar and engage the outer faces (4 of the frame, adjacent to the gap it therein, in the seated or attracted position of the plunger shown in Figure 1.

The pull bar of this invention comprises a fiat u elongated link if which may be readily stamped from a strip of metal and which has its inner end portion 18 received in a coaxial outwardly opening well 19 in the plunger head. The well extends inwardly slightly beyond the plane of the faces I 3 on the head of the plunger, and may be provided by forming an outwardly opening slot in each of a group of laminae at the center of the stack thereof which make up the plunger.

One of the rivets it which secure the plunger laminae together serves as a cross pin by means of which the link is secured to the plunger. This rivet passes through the well 59 and through a hole 2| in the inner end portion of the link, and the axis of the rivet intersects that of the plunger near the plane containing the inner faces i3 of the lateral extensions of the plunger.

The diameter of the hole ii in the link is larger than that of the cross pin so that the link fits loosely thereon and is free for limited universal swiveling motion within the limits defined by the walls of the well, it being understood that the cross section of the well is substantially larger than that of the link. The inner end of the link and. the bottom of the well are preferably rounded to assure clearance for this motion of the link.

Another hole 22 in the link, near its outer end, provides for connection of the link to the load to be actuated by the plunger.

Because the link has the aforesaid freedom for universal swiveling motion on the cross pin 20, perfect alignment between the solenoid and its load is not essential, the mobility of the link compensating for inaccuracies in the mounting of the solenoid. Because the inner end of the link is received in the well, and the cross pin is thus spaced inwardly of the outer end of the plunger to be closely adjacent to the plane containing the inner faces of the plunger extensions,

any lateral force component due to disalignment between the plunger axis and the load force will be exerted upon the plunger through a very short lever arm, and will thus have less tendency to cook the plunger askew.

Furthermore, not only does the single link pull bar of this invention have the advantage of simplicity and low cost, as compared with the previous type of pull bar comprising forward extensions of the side plates of the plunger, but it has the additional advantage of transmitting the load force to the plunger at or very near to its axis, as contrasted with the tendency of the spaced side plate extensions to receive the load force unequally and thus create a turning force couple upon the plunger.

From the foregoing description taken together with the accompanying drawing, it will be readily apparent that this invention provides an improved pull bar for the plunger of a solenoid which may be manufactured at very small cost and which will transmit the reaction of the load force to the plunger in such a manner that the tendency of the plunger to be cooked askew by misalignment between its axis and the load force will be minimized or even entirely eliminated.

What We claim as our invention is:

l. A solenoid having a plunger and a frame provided with an opening in which the plunger is endwise slidable, said frame having external pole faces flanking said opening and lying in a common plane normal to the axis of said opening, characterized by means on one end of the plunger defining a pair of opposite lateral extensions having substantially coplanar surfaces facing the other end of the plunger and adapted to seat fiatwise against said pole faces on the frame to define the attracted position to which the plunger is drawn in consequence of energization of the solenoid; further characterized by a substantially coaxial well in the plunger opening to said one end thereof; and further characterized by a thin link having one of its end portions loosely received in said well and having a swivel connection with the plunger in said well, which connection is defined by a localized contact between the link and the plunger substantially coaxial with the plunger and adjacent to the plane containing said surfaces of the lateral extensions, so that the free end of the link may have a limited degree of universal swiveling motion to compensate for any misalignment between the axis of the plunger and a load with which the free end of the link is connected and so that any sideward component of the reaction of said load will be transmitted to the plunger adjacent to the plane of said surfaces to thereby assure quiet operation of the solenoid by minimizing the forces tending to tilt the plunger.

2. The solenoid of claim 1 further characterized by the fact that the swivel connection between the link and the plunger comprises a pin fixed in said one end of the plunger at opposite sides of said well and passing loosely through the inner end of the link.

3. In a solenoid having a frame provided with a plunger opening and external pole faces flanking said opening and lying in a common plane normal to the axis of said opening: a stack of laminations secured together and cooperating to provide a plunger having a stem portion slidable endwise in the frame opening and lateral extensions at the front end of the stem to define an enlarged head on the front of the plunger, the surfaces on said extensions which face the rear end of the plunger being coplanar and flatwise engageable with said pole faces on the frame in the fully attracted position of the plunger, all of said laminations comprising the plunger being identical except for a plurality at the center thereof which have a notch opening to the front of the plunger and which cooperate to define a relatively narrow well coaxial with the plunger stem, the bottom of said well lying rearwardly of the plane of said surfaces on the extensions; 2, pin fixed in the plunger head and extending across the narrow dimension of said well closely adjacent to the plane of said surfaces on the extensions; and a pull bar for the plunger having one end portion received in said well and comprising a flat link having a thickness substantially less than the narrow dimension of said well and having a. hole in said portion thereof larger in diameter than said pin and through which the pin projects, so that said link has its outer end free for a limited degree of universal swiveling motion while its area of contact with the plunger is confined to a relatively narrow zone on the axis of the plunger stem.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,098,331 Bowman Nov. 9, 1937 2,158,430 Peterson May 16, 1939 2,332,438 Clifiord Oct. 19, 1943 ,338,775 Martin Jan. 11, 1944 2,466,592 Jencks Apr. 5, 1949 

